fix(moderation): policy viewer lists a stable rule and its legacy twin once (#321)

dedupePolicyEntries keyed on the raw recommendation, so m.ban and
org.matrix.mjolnir.ban for the same entity never matched and the rule
showed twice (both labelled "Ban"). Key on the normalised value; move
the pure helpers to policyEntries.ts with unit tests.

Fixes #321

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/features/room-settings/PolicyListViewer.tsx

@@ -17,6 +17,7 @@ import { Page, PageContent, PageHeader } from '../../components/page';
 import { useMatrixClient } from '../../hooks/useMatrixClient';
 import { SequenceCard } from '../../components/sequence-card';
 import { SequenceCardStyle } from '../common-settings/styles.css';
+import { dedupePolicyEntries, PolicyEntry, recommendationLabel } from './policyEntries';
 
 // ── Policy event types ────────────────────────────────────────────────────────
 
@@ -38,13 +39,6 @@ type PolicyRuleContent = {
   recommendation?: string;
 };
 
-type PolicyEntry = {
-  entity: string;
-  reason: string;
-  recommendation: string;
-  stateKey: string;
-};
-
 type PolicyTab = 'users' | 'rooms' | 'servers';
 
 // ── Helpers ───────────────────────────────────────────────────────────────────
@@ -53,13 +47,6 @@ function isGlob(entity: string): boolean {
   return entity.includes('*') || entity.includes('?');
 }
 
-function recommendationLabel(rec: string): string {
-  // `m.ban` is the stable value; `org.matrix.mjolnir.ban` is the legacy
-  // (pre-stabilization) recommendation still emitted by older bots.
-  if (rec === 'm.ban' || rec === 'org.matrix.mjolnir.ban') return 'Ban';
-  return rec;
-}
-
 /**
  * Fetch all state events of a given type from a room's live forward state.
  * Uses the raw matrix-js-sdk `getStateEvents` API which accepts any string type.
@@ -84,23 +71,6 @@ function extractPolicyEntries(events: MatrixEvent[]): PolicyEntry[] {
     .filter((entry) => entry.entity !== '');
 }
 
-/**
- * Merge policy entries from the stable and legacy event types for a rule
- * kind, de-duplicating by entity+recommendation so a room that emits both a
- * stable and a legacy rule for the same target isn't double-listed.
- */
-export function dedupePolicyEntries(entries: PolicyEntry[]): PolicyEntry[] {
-  const seen = new Set<string>();
-  const result: PolicyEntry[] = [];
-  entries.forEach((entry) => {
-    const key = `${entry.entity} ${entry.recommendation}`;
-    if (seen.has(key)) return;
-    seen.add(key);
-    result.push(entry);
-  });
-  return result;
-}
-
 // ── Entry row ─────────────────────────────────────────────────────────────────
 
 function PolicyEntryRow({ entry }: { entry: PolicyEntry }) {